While I was aiding Cream Machine (thin M4, The Gorge) on the weekend I ended up taking a fall and decking out. I was nearing the top, reaching up to place my next piece of pro when the #0 RP I was standing on ripped, and I landed on the ledge 9m below on my back. Below the #0 RP had been a bomber #2 RP, followed by a few nuts, most marginal. Turns out the force from my initial fall (4m?) onto the #2 RP was enough to break the wire (rated to 5.5kn) at the clip loop (see photo below). The marginal pieces below zippered. Even though the wire snapped and gear pulled, the force of my fall was reduced enough that I was able to walk away. I was very lucky.

Lessons learned:
- Test more - I tested all my pieces before weighting, but obviously not enough
- I could have used screamers
- Use the biggest piece of pro that will fit – although the #2 RP placement was good, it could have been substituted for a larger piece (read: higher rating, greater safety margin).
Marginal placements could have been backed up/equalised with other pieces
Don’t do aid unless you have a beard...

Out of curiosity, what belay device was your belayer using? The only aiding I have ever seen is in videos where the belayer is lounged out using a grigri... which always surprised me considering the differences in impact force compared to an ATC type devcie. On the other hand, I gather belaying an aider can be a tad mindnumbing so a self-locking device might be an appropriate compromise...

I did my first aid the other week and we had a quick think between a grigri or the atc and decided on the atc because we didn't want to take the chance of pulling gear out with the extra force.
not that I use a grigri ever myself anyway but i def wouldn't use a auto locking device on any trad routes, only on bomber fixed gear.

although, on the aid climb there was alot of " i wish i had a f@#king grigri being yelled" after 2+ hours of belaying.

I was down at Buffalo in early Feb and got scared witless on the Cream Machine! Glad to hear you're OK. Personally I found bounce-testing the most frightening part of what little aiding I've done. My difficulties are perhaps down to not having a beard...

I again heard the zing of rope, but unfortunately this time accompanied by the muffled 'whump' of somebody decking out...
Over on Cream Machine Trogster was on the ground, and all that remained on the route was a broken wire at 8m height plus a limp rope in one remaining piece at about 5m height.
Rushing over, I held him securely as he was writhing in pain and I was concerned that although he was still on belay that if he rolled off the ledge he would be in for more of the same, but at a considerable distance lower...
Things happen in a blur during such moments. There were plenty of helpful hands and after we made him a little more comfortable by removing the forearm thickness branch from under him that he had broken off the ledge shrubbery with his ribs/back, securing him with a sling anchor to the remaining portion of shrub to prevent his falling further, we were suitably concerned with the hoarse gurgling noises he was making, and expecting at any moment to see him start frothing blood from his mouth. His helmet was undone and coming off his head, and once he lay still for a bit his breathing settled and his responses were lucid and coherent.
Due his helmet being undone my thoughts were that he had crashed through the limb and probably broken ribs (or worse), plus taken a head knock. He informed us that he was sore but not in any pain that would indicate a broken bone or limb. Despite this advice we waited and watched with concern though reassuring him at the same time that all looked OK (which in fact it did), till we believed this ourselves! I was much relieved when he got to his feet and continued to act reassuringly normal, but even so, it was agreed by some of us that we would be keeping an eye on him for the remainder of the evening, despite his reassurances that he did not require taking to hospital to be checked out, nor wanting the pain killers that Wollemi offered him, as he felt that he was only badly winded. (He informed me later that he undid his helmet as a first reaction to not being able to breath easily). He was escorted up the access gully to the car and we then engaged in post-morteming what had happened, cleaning the climb and packing gear, as it was late in the day anyway.
On that point, Fish Boy led the climb to clean it. Many of the remaining persons were impressed at the aggressive testing Fish Boy utilised during that lead, and more fully realised that true testing involves sufficient bouncing to get the remaining gear on your harness flapping properly! I have now decided that it is one thing for someone like me to say this as instructional advice, but it is much more meaningful if demonstrated...

It turns out that he was on a #zero size RP that had been placed a move above the remaining broken wire, and in fact was reasonably high in his etts (ie had been on the placement a while), to make the next subsequent placement when the zero ripped. His fall of approx 1½ m broke the #2 RP at the base of the clip in loop, but by then the rope tension had (like the similar falls earlier) dislodged much of the thin remaining gear on the lower third of the climb, whilst he simultaneously zippered further placements till he decked and the rope was limp on the last remaining piece still intact on the climb. It was subsequently found that the krab that had been connected to the broken RP was also damaged due its gate spring becoming dislodged from within the base of the gate.
As a side note, I have noticed in the past that many small RP's break one of their wires where their wires join the head. This one broke at the clipping point primarily due to it being a relatively new item and not having been placed or 'cleaned' much, therefore not having had its wires worked over / stressed near the head with prior usage, and indeed if this had been the case it may have broken more easily, ... but this is academic; as the result is the same due this particular fall generated sufficient force to do the job anyway, even though the head remained in it's placement.
In hindsight I recall him asking me what strength the small size RP's are rated at, and I told him #3 is 370 kg, #2 is 190 kg, with the smaller sizes being less but this is mostly to do with the cable breaking strain and not the head shearing out of the placement. I now wonder if he 'put the mocka' on himself and set himself up for a 9 to 10m deckout?
~> He is now known by the group as 'Lucky Adam' and given the circumstances I doubt he will win anything in Lotto or similar for a long while, as I reckon he dipped heavily into the luck bucket on that occasion to come out of that one relatively unscathed.

What can we learn from this?
If facing a thin lead put the first piece in for an upward load as every piece on thin aid is a 'Jesus piece'.
Place the biggest gear one can that fits in any given placement for pro.
If the pro is ordinary/thin, back it up, ... multiple times if necessary, and equalise the matrix.
Aggressively test the placement as much as prudently possible and preferably more than tentatively.